Tow bar



B. PHILLIPS Jan. 25,1944.

'row BAR Filed July 10,1943

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B. PHILLIPS Jam-25,1944.

wow BAR Filed Jul 10; 1943 2 Sheets-Sheet 2 INVENTOR.

Patented Jan. 25, 1944 UNI TED STATES PAT ENT OFFICE TOW BAR Benjamin Phillips, Cincinnati, Ohio, as'signor fto Phillips Pump and Tank Company, Cincinnati,

Ohio, a corporation of Delaware Application July 10, 1943,8erial No. 494,190

10 Claims.

Thisinvention relatestoan adjustable tow bar apparatus which is used for towing airplanes by m'eans'of asuitable tractor or the like. The principal-objective of the inventionhas'been to provide the simplified tow bar structure having a hitch at it's one end adapted "for connection with the tractor and having means at its other end adapted for engagement with the airplane wheel struts.

Heretcfore airplanes have been moved about the field and to and from the hangars either manually, by :a crew of men detailed to that "duty, or by-means of tractor towed bars'designed to suit specific types of airplanes. Such tow bars have been of rigid construction and have been substantially useless for moving airplanes of types other than the "ones they are designed to fit. It has been necessary, therefore, that'the landing field or hangars have available-a variety oftow bar units of different. kinds and sizes 'in order that :the moving crew at the field might select the one required for each job. This'proeedure obviousl'y is not only time consuming, but is :still more undesirable for the reason that "the field rarely can be equipped completely with moving apparatus "suitable for all types of planes whichcall for serviceor repair. This is particularly true at emergency landing fields in war areas where :a :plane must be moved'quicklyir'om the field to conceal it from enemyiaircrait.

With these various factors in mind the purpose of the present invention has been to provide a universal tow bar which is :'adjustable through an almostinfinite varietyof dimensions to fitthe landing gear of any plane that must be moved.

Afurth'er objectiv'e'of the presentinventio'n has been to'provide a collapsible towb'ar which, when notin use, may be compactly'arranged-inasmall unit to facilitate the storage and the shipment of it.

.A:further objeotiveof thepresentinvention has been to :provide a wheelable'tow bar 'unit which,

ragged at one end, may 'be rolled about with little efior't. In this manner strength maybe built into the apparatus through'the use ofr'elatively heavy structural members without inconveniencing-its usage.

A still further objective of the present inven- .tion has been to provide 'a tow bar'comprising towing leg members,interconnected'through cross braces, which permit the legs to be spread apart freely and yet restrain closing or collapsing movement of the legs through uni-directional clutches arranged to be releasedby hand. These provisions enable the legs of the tow bar to be spread apart conveniently to the distance necessary to accommodate the particularplane which must be towed. Thereafter the clutches provide aigripping action whichprevents'the arms from moving together when the plane is being towed.

-A-still further objective of the present invention has been to provide a structure of this sort in which the cross braces distribute (and equalize the load to which each of the towing legs issubjected, and also provide resistance-against bending movements in these members.

The present invention also contemplates a tow -ba r in which the tractor hitch at the forward endofthe unitis mounted for movement'incompound directions so that the 'tow bar maybe arranged at various angular positions between .the plane and tractor to eliminate'undue downward strain upon the tractor or the-planeduring towingmovements.

preferred embodiment of the tow bar in which these principles are utilized is shown in the accompanying drawings and, 'from the fore- .going explanation and the followingdetaileddescrip-tion, those skilledin theart readily willcom- .prhend the various modifications to which the invention is-susceptible.

in the drawings:

Figure 1 is adiagrammatic view showing the tow bar interconnecting a tractor or othertowing vehicle with the landinglgear of an airplane during usage of the-apparatus.

F'igure -2=-is a plan view of the tow barapparatus of the invention.

Figure 3 is a cross sectional viewtaken on the d .line33 of Figure 2.

Figure 4 is an elevation taken-along the lines 3 E of Figure :2. This view shows the interconnection-of-a strut with the tow bar arm.

Figure :5 is-a view taken along-the lines 5-5 of Figure 2 and is similar to Figure 4 which shows the details of s the cross brace clutch.

Figure -6;i s a .cross sectional view taken on the line li -E of Figure-:5.

JEigure 7 .is-an elevation showing wheel mount- 'ing details-as taken on the line 'l.--'! of Figure 2.

Figure 8 is a cross sectional view as taken on .thelineB-tof Figure 7;

Figure :9 is across sectional view taken on "the line ll-Bmf =F'igure'2.

Figure 10 is an enlarged iplanwiew "showing the arrangement for shackling the ends of the 'tow bar :arms to theairplaneilanding gear.

;-F:igure 11 rise, cross "sectional elevation taken on'the line l-II [of Figure 10.

In --.the preferred embodiment shown in the which may be made conveniently from wrought: iron pipe and metal plate whichafter fabrication "q' iifi bl -ii l reduces the cost of the apparatus, noerrterisiye;

may be assembled by welding." .l'I-

machining of the parts is required.

The legs 2 are comprised ofubular are welded to 'tthe'cre's'peic'tive anglei' races e. each of the clevis-rninbrs co'inprises-a back web H which is held-to the-anglesurface and {arms l2--I2 extending outwardly therefrom at an angle with respect t'o' thear sg ormema n legs-'2. The arms l2 of the clevis ""re spaced apart a distance greater thanth s of-the clevis lfl whereby the latter fitsint pivot pin l3 passes through-"both setsfof' ar s to constitute the pivotal axisbetweeri the legsj 2 The pivot pin is held in 'placeby ""ofcotter pins 4 r A:

A hitch block I5 is disposed between theaiihs 12 of the inner clevis It). This block is' traversed by the pivotal shaft l3 and extends forwardly from the apparatus to carry an'eye member Hi which is pivotally mounted to the block in a plane substantially parallel with the plane of the arms through the pivot pin [1. Therefore, the "eye member l6, which in a simple convenient form may be a strap having its arms connected to the pivot shaft I1, is 'free to move. in an up and down direction and, at the same time, rotate horizontally about the shaft l3. The clevises 9 and I0 extending angularly from the legs 2 toward one another space the arms apart at their forward end to provide for compaction of the apparatus as described at a later point in the specification.

At the rearward ends of the 'legs 2 they are provided each with a fork piece l8 which, similarly to the clevises 9 and I0, pivotally carries a cooperating fork member 19 through a shaft 20. Connector brackets 2! of U-shape are rotatably setitn which at the forward end of the apparatus a p severed angularly as at 8. Clevis members 9 and 20 mounted to the flat rearward faces of the forks I9 through the pivot pins 22. In the preferred structure these pins are journalled in bushings 23 which reside in suitable bores in the mating webs of the fork connector elements l9 and 2f respectively.

Thus each leg terminates in a bifurcated connector elementwhich is rotatable about the axis of the leg through the pivotal connection furnished by the pin '22 and may also be swung through an arc, in vertical directions, through the pivotal mounting provided by shaft 20. This arrangement enables the point at which the connection isto be made to be altered to suit the conditions necessary for connection of the apparatus to a wide variety of airplane types.

For the actual connection, each connector fork 2! is traversed by a keeper 24 which, as shown in Figure. 11, has an annular groove 25 at its upper end adjacent an enlarged head. A latch 26 1s pivotally mounted on a side arm of the con- -plane may be accomplished in various ways.

" e'ye bolts are provided at the landing struts then "the fork is adjusted to straddle the eye bolt and .at-gthe td nector bracket through a pin 21 and the latch has communicating bores, one of which is sufficiently large to clear the head of the keeper while the other just fits the annular restricted groove. Therefore, by shifting the latch until the smaller bore thereof embraces the annular groove, the keeper 24 is held, positively, in position. The keeper pin is..attached to..the forlnthrough a he connection of the apparatus with an airthe keeper. is passed. through the fork and eye a fo or if cbhain w may be passed around the strut after which-the keeper pin is dropped in place.

At the forward ends of the legs brackets 32 are fastened tothein'. 1 Each bracket comprises spaced apart. tubular portions- 33 embracing the l'eg and a :iconn'e'ctor! lplate 1 -3 4. T which: T extends laterally -fromtthe. tubular: portions 33 in: onset relationshipltoi the: axis 'thereof." i The i offset connector platesearexoppositelysarranged' "upon legs 2, one

de f .th' *legs and theoth'er at "the bottomi:

Similar brackets are provided on the le'gs *at the rearward-portioris of I the legs except that these are'slidable 'upon thlegs and are equipped with mini-directional:.:clutches;: Cross bracesf=3 6 interconnect theI respective stationary bracket 'plates'i34. with t the. slidable-brackets 35." In view :ofithz :ofisetti'ng 'z'of the Tp'late portions 34 of the brackets. thescrossi struts clea'r one another yet iresidetsubstantially. in-tthe lplan 'of -the' legs 2;. I

.- FEachE ofther:clutch gbrackets 35 comprise's a clutch housin'g. made u "of. side walls 31 which surround substantiallyron 'l-halro'f the leg 2 and extend'ilaterally aitherefrom; at the opposite side, forr interconnectiontwith Ion:.another through" a cross,.web::38." Each of thecarnisihasfan aperture 3 SJther'ein providing a: tapered or cam surface 40.

The; riournalsjof; a: ressure .roller 4| extend through .fthe iaper'tures'? whilel Ithe roller 1 itself is arcuately lgro'ovedattits central: portion, as at r 42, to approximatetheicontour.ofithe leg. Thecam surfaces 40,:atthe'point thereoflfarthest removed from the, leg, clearsithe' journaliof the roller and permits it to:.' rota'te.freelyrwhile resting 'upon the leg. However, this surface converges toward the leg so that'the clutch-roller, moving freely along the leg 2,:moves'gtaidistance sufficient for engagement of the'fiuppe'r; portion of the roller journal with the tapered Surfacathereby' moving theroller axially intop'ressure engagement with the leg. This in turn causes the leg to be moved into frictional engagement with'the arms which embrace it at the lower side, thus causing-the bracket frictionally to grip-the lgand be re strained against sliding movement. The cam surfaces 40 converge toward theileg in adirection forwardly of the apparatus, that is, toward the front or tractor hitch end. a i a Releasing handles 43 are provided at the clutch assemblies. Each of these comprises a 'ugshaped piece straddling the clutch housing and'having its side arms residing adjacent theside walls 31 thereof. The arms 44 are bored and screws 45 pass through'them into threaded engagement with the pressure roller at its opposite ends while the upper portions of the side arms 44 offthe handles are slotted longitudinally as at 46: A

'pin 41 fastened to the clutch housing extends laterally thereof through these slots "46 and acts rtherefore as an axle around "which 'the assembly of the releasing handle :and clutch roller may be tilted.

When the roller advances to the forward en'd -o'f the apertures .39 of "the 'clutch housing the releasing handle therefor assumes the angular position as shown best in Figure 5. lm-this :position the clutch is closed with the roller thereof pressing downwardly upon the leg 2 urging it into frictional engagement with the portions :3 of thec'lutchhousing which embrace the roller part of the leg as shown in Figure 6. 'When the :handle is gripped and tilted upward and iorwardly so as to assume a more vertical position the roller is moved in a backward direction, its journals clear the cam surfaces of the apertures '39 and the roller 'thereforeisrelieved of its-pressure engagement'with the legs.

'The clutch brackets, at any time, may be moved relatively in a rearward direction of the 'legs'to permit them tobe spread. 'Thus, if the clutch is closed, this m'ovement fr'ees it. On "the other hand, during towing operations the rollers'of theplut'ches, trackingupon the l'egs, ad. vance downwardly upon the cam surfaces and effect the bind action ,just described.

Plate members 48 extending laterally from the clutch housings '35 atthe lower portion there- "of provide for pivotal connection of the cross braces '4 thereto as through the pivot pins 48a. In the preferred structure, as shown in Figure 6, the-clutch is built from a single pieceo'f-metal which, from the plate 48, is bent upwardly "to embrace about a quarter of the leg contour, then, at a point above the leg, the metal is 'bentover to form the topwalltiian'd'bent downwardly again with its 'lower'portion embracing an opposite portion of the periphery of the leg 'to form the friction seat. This latter portion may be welded to the plate 48 'as'in'dicated, 'whileth'e apertures 39 and the releasing handle for the clutch may be formed by's'uitable blanking and stamping operations. The pin fla'lso may be fastened to the'top 'wall'of the clutch housing as by welding.

For'thepurpose of enabling the tow bar apparatus'to be trundled from one point to another at the air field or the hanger, casters are provided as indicated generally at B. In the preferred structure these units "are located on the legs at the rearward'p'or'tion thereof forwardly of the attachment apparatus. Each legis provided with a collar 4'9'whichis rotatablethereon 'and'the legs 5ll50 are heldto'this "collar'to reside in spaced parallel relationship' to one another. These constitute a fork 'for the caster. The fork is bore'dtransversely at its lower portion to receive an axle 5!, with spacers 52 being located at the inner and outerfaces o'f'the legs "respectively. Cotter pins '53 pass through the axleto holdit'in placeagainst the outer washers and 'a caster 54 is mounted on the axle so that it may rotate.

For the purpose of adjustably supporting the caster unit, a bracket 55 isprovided having portions 56 embracing and attached to the leg 2 at opposite ends of the collar 49 and a support member 5! which is bent'up to extend laterally 'from'the leg as shown in Figure-8. The support meniber'51may be formed from 'the'rnet'al lying 'in-between the leg embracing 'portions55. Ai-U- shaped bracket "58 is fastened, -flatwise, against the race of "the plate 51 to provide "upper and lower "sup ortin ledges which are spaced apart from Zone another. These ledges are bored 'to receiieailock pin fifl'which'hasarhandle manpper end. Intermediate the support ledges 58 -a pin 60 :is passed transversely through the .lock

' per ledge 58. This spring therefore urges the lockpin -towa1'r.i leg-2. Collar "49 is provided with radial bores located in sp'ac'ed relationshipin its periphery to receive the lock pin. 'One of these bores is entered by the lock pin 59 when "the easterlies in aplane lateral to the plane "ofthe legs 2 while bores at opposite sides thereof 'are employed to enable the casterto be held in-right and left-hand horizontal positions as-shown by the dotted lines, in which event they lie substantially flush with a plane passingbetween the leg. Through this arrangement the casters "may 'b'e' h'eld in the lateral position when they are to be utilized and may be thrown "off, to one side or the other, during towing operations or when they would otherwise interfere with usage-of the apparatus.

a In respect to the'mounting of the'casters the inventionucontemplates a structure in which the casters are-supported at a slight outward "camber whereby when the bar itself is being towed the 'cambering of thecasters will cause "them to move relatively toward'oneanother and thereby move the logs into a position of substantially parallel alignment. Conversely, when the towing apparatus is 'lined updirectly in front of an "airplane which is to "be "towed the carribero'f the casters will cause the legs to slide automatically'as the unit is backed up toward the plane. This to a. ,great'extent eliminates the nece'ssityfor two uperators to complete attachment of the "tow bar to the landing gear.

At the "rearward end of eachleg it is also provided with 'a'strap 53; this is a U-sha'p'ed piece which fits around "the legs and extends'laterally therefrom in the plane of'the legs and toward one another. One of the U-shaped pieces has its 'endwise portions arranged to fit'btween the endwise'portion'of the other andtransverse bores "64 are provided to receive "the keeper pin 24. Therefore, as the legs arebrought together the str'apBB-on the respective legs is brought into engagement'and'when the bores therein areali'gne'd the keeper pin may be dropped through them to holdthelegs in closed relationship. This'isparticularly desirable for shipping purposes sothat the'apparatus maybe handled convenientlywithout danger "of the legs being spread apart inadvertently.

Itmaybe noted "that the laterally'ofiset leg portions Sextend angularly'toward one anotherlfrom the forwardends of the legs 2 so that they -are spaced apart from one another at this portion of the apparatus. At the other end the lateral extensions of the brackets 63 also hold the legs apart when they areinsubstantially parallel relationship. When the 'legs'arearrangedin this position the space between them accommodates the cross rods 36 so that'the entire 'apparatusis substantially uniform in width throughout its length-when closed and therefore readily adapted to be packed or'stored in a minimumof space.

When the towing unit is to beusedthe keeper pin is removed'from the strap 63 and thelegs are spread apart a distance "suitable for attachment of them to the landing :gear "of the airplane. Thereafter the "clutches prevent closing move directional clutch devices interposed between said cross braces and said legs.

8. A tow bar comprising leg members, a hitch member adapted to be connected with a towing vehicle, means extending laterally from said leg members into pivotal connection with said hitch member whereby said legs will be spaced apart from one another when they are arranged in sub stantially parallel relationship, clutch devices slidably carried by said legs, means carried by said clutch devices for preventing slidable movement thereof along said legs in a given direction without restraining movement thereof in an opposite direction, cross braces each having one end thereof pivotally connected to a leg and the opposite end thereof pivotally connected to a clutch device located at the opposite leg, said cross braces overlying one another and being arranged to 00- cupy the space between the legs when the legs are arranged in substantially parallel relationship.

9. A tow bar comprising a hitch member adapted for attachment to a towing vehicle, leg members pivotally connected to said hitch member at one end thereof, means at the opposite ends of said leg members for effecting connection thereof with the landing gear of an airplane, clutch devices comprising members embracing said legs and slidable thereon, pressure rollers arranged for engagement with said legs, means presenting cam surfaces for urging said pressure rollers into pressure connection with said legs as said rollers are tracked upon said legs in one direction of movement of said clutch devices on said legs and for relieving said pressure rollers from pressure engagement with said legs through sliding movement in an opposite direction, and cross braces each having one end thereof pivotally connected with a leg and an opposite end thereof pivotally connected with the clutch devices on the opposite leg.

10. A tow bar comprising a hitch member adapted for attachment to a towing vehicle, leg members pivotally connected with one another at said hitch member whereby said legs may be arranged in diverging relationship, means at the opposite ends of said legs for effecting connection thereof with the landing gear of an airplane and casters mounted res'pectively'at the latter ends of said legs, and providing the means whereby said tow bar unit may be rolled into position, said caster means being arranged in cambered position whereby the legs are caused through said cambering to move toward one another when the tow bar unit is being towed and, conversely, to be spread apart from one another when the tow bar unit is being pushed in a backward direction.

BENJAMIN PHILLIPS. 

